SSL and TLS Terminology

SSL was originally defined by Netscape. The first publicly released version, SSL v2, came out in 1994. Several vendor-specific variants appeared, notably Private Communications Technology (PCT) from Microsoft. PCT was effectively a rival to SSL v3 when that came out in 1995. The Internet Engineering Task Force (IETF) took on the task of creating an industry-wide standard, and developed what was effectively SSL v3.1. However, they adopted for this the vendor-neutral name of Transport Layer Security (TLS). The terms TLS and SSL are sometimes used interchangeably. In this book we generally keep to the term SSL.